Abstract
The catalytic behavior of alkaline earth carbonates of Mg, Ca, Sr and Ba on the gasification of carbon were investigated under high pressures of CO2 by using a thermobalance, fixed bed flow reactor system and temperature-programmed X-ray diffraction. The carbon material used was prepared from phenol formaldehyde resin. It was mixed with respective carbonate of 0 .5 atomic % in a mortar grinder for 1 hour.
It was found from nonisothermal thermogravimetric measurements that the gasification of the pure carbon showed an increase in conversion with increasing CO2 pressure, and the rate of gasification was proportional to the square root of CO2 pressure. Addition of four carbonates, Ca, Sr and Ba, except Mg, had appreciable catalytic actions, but their rate constants were not so much large increased with the increase of CO2 pressure. For MgCO3, little catalytic effect was observed only between 750°C and 800°C at 49.5 atm of CO2 in the flow reactor system.
According to the temperature-programmed X-ray diffraction, high catalytic activities were obtained when the carbonates coexist with their oxides. Such results will confirm the cyclic catalytic mechanism of oxide-carbonate, previously stated.
